DESCRIPTION: Synapses are most fundamental to the function of a nervous system. C. elegans is an excellent genetic model system for finding genes and elucidating pathways because of its sequenced genome and the abundance of molecular biology tools and mutants. Due to the simplicity of its nervous system, many breakthroughs have been made in C. elegans for understanding molecular mechanisms in the patterning of the nervous system and synapse development. The current bottlenecks are in the manual and non-quantitative techniques such as visual screens, limiting both the throughput of the experiments and the phenotypes one can examine. Our long-term objective is to develop technologies and to understand how genes, age, and the environment together define and continue to remodel the nervous system of an organism. In the last funding period, we have made large progress in hardware system design (including microtechnologies and automation technologies) and software for quantitative characterization of phenotypes. The objective of this continuation project is to further engineer superior micro devices for large-scale live imaging and quantitative imaging technologies, and combine with the power of genetic and genomic approaches to study synapse development in this in vivo system; genes and pathways emerging from this study could potentially become targets of therapeutics in neurological disorders. We have shown in the previous phase of the project that quantitative microscopy-based approaches can indeed enable identification of novel genes and pathways that conventional approaches cannot. In the continuation phase, we will further optimize on-chip rapid and high-content in vivo imaging techniques, and in parallel further develop algorithms and quantitative measures for the analysis of such high-content data; we will screen based on novel synthetic phenotype unobservable by eye; we will also exploit powerful genomic techniques to identify loci and potential multigenic interactions that shape the synapse morphology. These experimental approaches will identify genes that cannot have been identified otherwise because of the difficulties associated with the phenotypical profiling, but addressed using our engineered techniques here. The approach is innovative because the technology developed here dramatically increases the throughput, sensitivity, and accuracy of the experiments, and truly enables the utility of extremely powerful genetic and genomic methods. The proposed research is significant because it fills the urgent need in high-throughput and high-content screens as well as identifying novel genes and pathways. In addition, besides the contribution to the specific neurobiology, the technologies are widely applicable to areas such as developmental cell biology, and to other small organisms such as fly larvae and zebrafish embryos.